In immune reactions in the body, cytokines produced from various immunocytes control direction of the immune responses. In this regulation of immune responses, it is helper T cells that play a central role, and they are classified into subsets Th1 and Th2 depending upon the type of cytokines they produce. Th1 type cells are known to produce mainly e.g. interleukin 2 (IL-2) and interferon γ (IFN-γ) and to be concerned with cellular immunity such as protection against infection by e.g. virus and bacteria. Th2 type cells are known to produce mainly e.g. interleukin 4 (IL-4), interleukin 5 (IL-5), interleukin 6 (IL-6), interleukin 10 (IL-10) and interleukin 13 (IL-13) and to be concerned with humoral immunity such as protection against parasitic infection and antibody production from B cells. However, it has been clarified that if control of such biophylactic mechanism dysfunctions or deteriorates for some reason, hyperactivation or imbalance of immune function may occur, thus inducing or deteriorating various diseases.
Immune response of Th2 type induces or activates, due to its hyperactivation, allergic inflammation reactions such as immediate type allergy with which IgE antibody or mast cells are mainly concerned, and delayed-type allergy with which eosinophils are mainly concerned, and is deeply concerned with induction or deterioration of various allergic diseases such as urticaria, food allergy, anaphylactic shock, hypereosinophilic syndrome, asthma, allergic rhinitis, allergic conjunctivitis and atopic dermatitis. Further, abnormal hyperactivation of immune reaction of Th2 type is deeply concerned also with systemic autoimmune diseases in a pathophysiologic state where antibody production or humoral immunity is hyperactivated, such as systemic lupus erythematosus. It is considered to be important to control the immune response of Th2 type in order to treat or prevent such allergic diseases. On the other hand, immune response of Th1 type induces or activates cellular immune responses due to its hyperactivation, and is deeply concerned with induction or deterioration of organ specific autoimmune diseases such as chronic rheumatoid arthritis, type I diabetes, Hashimoto's thyroiditis, myasthenia gravis and multiple sclerosis. Further, cellular immune response of Th1 type is deeply concerned also with graft rejection accompanying organ transplantation. It is considered to be important to control immune response of Th1 type in order to prevent or treat such autoimmune diseases or graft rejection after transplantation.
Patent document 1 discloses amide compounds effective as cytokine production inhibitors, which, however, include no thioamide compounds.
Patent document 1: WO02/51397